ETL Reference SDK should gently handle permission errors

When the ETL reference SDK is used with a Sandbox, it should check if the appropriate permissions are granted and fail gently stating not enough permissions are granted.

Additionally, the individual call operations should provide appropriate error-handling when not the right permissions are granted to the integration.

Start by tracing the Java ETL reference SDK's Sandbox permission path and the individual call operations mentioned in the issue. Determine the expected gentle response for insufficient permissions, then verify both the initial permission check and per-operation handling with the relevant Sandbox scenario or tests.

Written by the indexing model from the issue text.